ArticleCategory: [Es gibt verschiedene Artikel
Kategorien]

AuthorImage:[Ein Bild von Dir]

TranslationInfo:[Autor und Übersetzer]

AboutTheAuthor:[Eine kleine Biographie über den
Autor]

Katja is the German editor of LinuxFocus. She likes Tux,
computer graphics, film & photography, travelling,
Montréal and the sea. Her homepage can be found here.

Abstract:[Hier sollte eine kleine Zusammenfassung
stehen]

In this article we take a look at dia, a diagram creation
program.

ArticleIllustration:[Das Titelbild des Artikels]

ArticleBody:

What is dia?

Dia is a program for drawing lots of different kind of
diagrams. It starts where your presentation tool stops,
providing you with all important forms and shapes for lots of
specific tasks.
The latest version as of this writing is dia 0.93.
If you have worked with other graphical programs under Linux
like e.g. The Gimp before you will find working with dia very
easy and straightforward.

Creating a flowchart diagram

In order to give you an impression of dia let's look at how
to create a simple flowchart. We will not describe all
possibilities dia offers. If you go to the dia homepage at
http://www.gnome.org/projects/dia/ you will find very good
documentation for the options and possibilities mentioned and
not mentioned here.
Start dia if you haven't started it already. Now you will get
a toolbar.

Under File you can open a new file or an already existing one.
You can have open as many diagrams as you wish and also
copy/paste from one to the next is no problem. I find this very
handy. If you want to reuse parts of an already existing
diagram you can easily copy/paste, you can look at slightly
different versions of the same diagram to see which you like
best, if you have a complex diagram and don't want to work with
layers you could design everything in several different
diagrams and then copy/paste it together etc. in case it is
needed in one diagram..
In our case we choose "new" to create a new diagram from
scratch. After clicking "new" a new empty diagram opens and you
can start working.
In the main menu below the one with "File" you find all kind of
operations like adding text or several more general objects
that are useful for all types of diagrams. Then if you click on
the field that has "Assorted" as its default you get a pop up
menu with all the areas dia offers special objects for. Of
course you are not restricted to use only one set for your
diagram but are free to mix them as much as you please. To get
the shapes of a flowchart for our diagram we click on
"flowchart" and all possible shapes become visible.
In the first phase of creating the diagram we can concentrate
entirely on the content and the general layout of our chart.
After we are satisfied with this we will make the changes for
the final design.
In a simple diagram we only need the decision and predefined
process boxes that we want to fill with text and connect
through arrows. Click on the decision box in the flowchart
objects toolbar and then on the empty diagram. In the diagram
you work similar like in an image of The Gimp. Left clicking on
an object selects it. By right clicking a menu with your
options appears and by clicking the middle mouse button you
sometimes also get some more options, e.g. you can change the
properties of an object, flip it horizontally or vertically,
add a corner/ a segment to a line/curve etc..
Okay, you have added your first object. As it is an object from
the flowchart menu it already knows about text and you can
simply start adding your text inside. (If you use other objects
you simply click on T in the main menu to add text and later
align text and box with each other. To align them select them
by drawing a big box around them. If both are really selected
go to Objects-->Align and decide how the text should be
aligned). Add all the objects you need and fill them with text
until you are satisfied. To connect your objects with arrows
you can choose between several line types. Depending on the
kind of your diagram you will be able to easily decide which
one is best for you. In the main menu at the bottom you can
determine the general design of your line. If you want an arrow
you simply choose an arrow in the right menu.
In case you want your lines "snap to grid" you go to the File
menu in the main menu. There you find a field called
"Preferences". Click on it and choose "snap to" under "Grid
lines" if you want straight lines that snap to the grid lines.
After that save your diagram as whateveryouwanttonameit.dia
with "Save as". Then close it and reopen it again. (Changes
will only get effective with the next diagram window that you
open, not with already open ones.) If you now add your lines
they will snap to the grid. Especially if you want to print
your diagram afterwards you will find "snap to grip" very
important to avoid strange looking lines.
That's all you need for a basic diagram. That was easy, wasn't
it? So now you can work on the specific design. If you want to
try several versions it's probably a good idea to save your
diagram now as a .dia file in case you haven't done so
already.
Let's see what we could change now to make our diagram look
more interesting and to emphasis the important points.
Let's say we want to change the colour of the text. There are
several options. To change the text of a single box select that
box by a left click, then a click on the middle mouse button
and on "Properties". A menu appears where you can change the
style and colour of the line as well as the text colour, font
(there are always three fonts available,sans, serif and
monospace, other postscript fonts can be added by the user
through a standard font requesters), size and orientation
(left, centre, right).
If you want to change e.g. the colour of several objects at the
same time you need to select the objects you want to select,
then right click in the diagram-->Objects-->Group and
then you can change the text or the look and feel of all those
objects by right clicking again and then
Objects-->Properties. (You always need to go to "Properties"
to change the properties of your objects now).
To select your objects the best way depends on what kind of
objects you want to change. If e.g. you want to change the line
width of all decision boxes you can easily select them all by
clicking on one and then right click, Select-->Same Type.
Now all decision boxes in your diagram are selected. There are
more options like this, read the manual to find out more. But
if all else fails you can still click on each object you want
to select while pressing shift down.
As an example I created a diagram that describes how you can
contribute to LinuxFocus:

Click on the diagram to see it in full
size

To add images to your diagram that are in a normal image format
like png, jpg, gif etc. you click on the image icon in the main
menu and then on your diagram. A selection with the text
"Broken image" appears. Now you click on the middle mouse
button and on "properties" and then you can browse for an image
in your files. After clicking "ok" or "apply" the image appears
in your diagram.
To save your diagram in a format like png,jpg, gif etc. click
File-->Export, then enter the name and the extension e.g.
png that it should have. Click ok. A new window opens telling
you the size of the image. If you want it bigger or smaller you
can change the values here. Note however that if you make it
too small your text won't be readable anylonger. If you want
your diagram to be readable in a certain size you can orient
yourself on the blue lines that indicate the size of one page
while drawing.
To print your diagram you should first go to File-->Page
Setup and scale the diagram down (with the scale option).

I find dia a very useful and helpful tool for creating
diagrams. Still I am really missing the option to freely rotate
objects. Some objects can at least be flipped horizontally or
vertically but to have more options here really would be great.
According to the dia website the programmers are already
working on a solution though so you can probably expect this
feature in any of the future versions of dia. Sometimes the
undo button doesn't work properly and from time to time the
program crashes. But taking into account that the current
version isn't even 1.x yet it has all the potential to become
an excellent program with a little bit of more time.
Happy diagramming!